Which bone-marrow cell type is most severely affected by irradiation?

The bone marrow cell type most severely affected by irradiation is lymphocytes. Lymphocytes are a type of white blood cell that play a crucial role in the immune system, helping to detect and fight off infections and diseases. Because they are rapidly dividing cells, lymphocytes are particularly sensitive to the damaging effects of radiation.

When irradiated, lymphocytes can be significantly impacted due to their high turnover rate and the need for continual production from stem cells in the bone marrow. This sensitivity makes lymphocytes one of the first cell types to show signs of damage following exposure to radiation, leading to a reduction in immune function and potentially resulting in immunosuppression or increased susceptibility to infections.

In contrast, lipocytes (fat cells) and neurons are not as directly affected by radiation exposure when compared to lymphocytes, as they do not have the same rapid division rates or role in the immediate immune response. Erythrocytes, or red blood cells, while important, are also produced from precursor cells in the bone marrow and may not be as severely affected in the acute phase since they have a longer lifespan in circulation. Thus, their immediate response to irradiation is different from that of lymphocytes.